1. Field of the Invention
The present invention relates to wireless communication, and more particularly, to an apparatus and method of accessing to a network of relay nodes in a wireless communication system.
2. Related Art
The 3rd generation partnership project (3GPP) long term evolution (LTE) which is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) have been introduced as 3GPP release 8. The 3GPP LTE uses an orthogonal frequency division multiple access (OFDMA) in a downlink and uses a single carrier-frequency division multiple access (SC-FDMA) in an uplink. The 3GPP LTE adopts multiple input multiple output (MIMO) having maximum four antennas. Research is now underway on 3GPP LTE-Advanced (LTE-A), which is a major enhancement to 3GPP LTE.
As a representative technology newly added in the LTE-A system, there are carrier aggregation and a relay. The carrier aggregation is used to flexibly expand an available bandwidth. The relay increases coverage of a cell, supports group mobility, and allows a user-centered network arrangement.
A relay node, which is a sort of network node, needs first to access to other network nodes (base stations or other relays) and then, to activate network functions in order to manage user equipments.
However, when receiving an access request from the relay mode, a base station does not unconditionally allow the access request but determines whether or not allow the access request of the relay node under considering various conditions. For example, when the base station does not support network configuration or has no sufficient radio resources supporting the relay node, the base station does not allow the access request of the relay node. After the access request is rejected, the relay node retries the access request with other base station.
The access attempt to the network node that does not allow the access of the relay node may unnecessarily delay services. When the relay node supports the group mobility, the elay due to the unnecessary access attempt may significantly degrade quality of service provided to user equipments managed by the relay node.
There is a need for preventing the access delay of the relay node.